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Transient Expression of Foreign Genes in Insect Cells (sf9) for Protein Functional Assay
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Published on: February 22, 2018

Baculovirus inhibitors of apoptosis (IAPs) block activation of Sf-caspase-1

S Seshagiri1, L K Miller

  • 1Department of Entomology, The University of Georgia, Athens, GA 30602, USA.

Proceedings of the National Academy of Sciences of the United States of America
|February 12, 1998
PubMed

Insights

Insect Sf-caspase-1 induces apoptosis in Spodoptera frugiperda cells, similar to mammalian caspase-3 but unlike caspase-1. Baculovirus inhibitors P35 and IAPs differentially block caspase-induced apoptosis.

Area of Science:

  • * Molecular Biology
  • * Cell Biology
  • * Biochemistry

Background:

  • * Caspases are key regulators of apoptosis, a programmed cell death process.
  • * Understanding caspase function in insects is crucial for insect biology and pest control.
  • * Mammalian caspases (caspase-1, caspase-3) and insect caspases (Sf-caspase-1) share conserved roles.

Purpose of the Study:

  • * To investigate the apoptotic activity of insect Sf-caspase-1 in Spodoptera frugiperda (Sf-21) cells.
  • * To compare the function of Sf-caspase-1 with mammalian caspases-1 and -3 in insect cells.
  • * To determine the inhibitory mechanisms of baculovirus anti-apoptotic proteins (P35 and IAPs) on Sf-caspase-1.

Main Methods:

  • * Transient expression of Sf-caspase-1 (pro-form and processed forms) in Sf-21 insect cells.
  • * Co-expression of Sf-caspase-1 subunits with mammalian caspases.
  • * Treatment with baculovirus inhibitors P35 and inhibitor of apoptosis proteins (IAPs).
  • * Monitoring apoptosis induction and caspase activation.

Main Results:

  • * Active forms of Sf-caspase-1 induced apoptosis in Sf-21 cells.
  • * Sf-caspase-1 activity resembled mammalian caspase-3, not caspase-1.
  • * Baculovirus P35 inhibited apoptosis induced by active caspases.
  • * Baculovirus IAPs blocked pro-Sf-caspase-1 activation but not active caspase-induced apoptosis.

Conclusions:

  • * Sf-caspase-1 activation is a key event in initiating apoptosis in insect cells.
  • * Baculovirus IAPs inhibit apoptosis by preventing pro-caspase activation, distinct from P35's mechanism.
  • * This study elucidates distinct caspase activation and inhibition pathways in insects and mammals.

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